“When I accepted the position in 2002, I anticipated serving as chair for a period of 10 years, having a vision of what I hoped to accomplish during that time. I approach the age of 65 next year having served as chair of two anesthesia departments — UMass, then BWH — over the last two decades.

“I have always felt that a leader is most effective during the first decade of service, after which time there can be diminishing returns on the energy invested in the challenges faced,” Vacanti wrote. “I feel that is certainly true in my case, and that by this measure, I am two years past due in making this decision.”

Vacanti did not respond to a request to comment on his decision.

In late January, Vacanti and a team of Japanese collaborators published a pair of scientific papers in the journal Nature that stunned colleagues, suggesting that it was possible to create powerful stem cells, that can develop into any tissue in the body, simply by dipping mature cells in an acid bath for half an hour.

Errors were found in the work, including images that were misrepresented.

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An investigation by RIKEN, the Japanese research institution where many of the scientists work, found evidence of scientific misconduct by Haruko Obokata
, the Japanese scientist who led the research and who worked in Boston under Vacanti’s supervision for some of the experiments. It is not clear whether the Brigham is doing a similar review of the research that was conducted here, because the hospital has a policy to not confirm or deny whether such investigations are taking place.

In an e-mail earlier this year, Vacanti described the role he played in supervising Obokata. He and another Brigham researcher, Koji Kojima, “developed the initial experiments with Dr. Obokata, and then met regularly with her to develop, design, review, and discuss the results of many of the experiments reported in the first paper. Later experiments and revisions to the manuscripts were, to a large degree, designed and overseen by our collaborators at the RIKEN, with intermittent updates given to us from Japan,” Vacanti wrote.

Elsewhere, the revelation of errors and alleged misconduct in the high profile work has put intense pressure on scientists involved in the work, especially in Japan. To the shock and sadness of stem cell scientists around the world, a key author of the papers and a prominent scientist, Yoshiki Sasai, committed suicide earlier this month.

Even though several top laboratories have sought to repeat the technique, none have reported success. Many scientists do not believe the technique works. But Obokata has been given until the end of November to try to repeat the experiments under careful surveillance.